Optical Properties of Front and Second Surface Silver-Based and Molybdenum-Based Mirrors

Abstract

Abstract-The solar reflectors used in Concentrated SolarPower (CSP) technologies are either front-surface or second-surface mirrors. The advantage of second-surface mirrors over front-surface mirrors is due to the fact that the reflective layer in second-surface mirrors is covered from the front-side by glass, which allows protection against degradation factors and aggressive outdoor conditions. In this work, front surface mirrors and second-surface mirrors were prepared based on two reflective layers (Silver and Molybdenum). A comparison between the optical properties of the two mirrors' architectures was conducted using a Perkin Elmer LAMBDA 950 UV/Vis/NIR Spectrophotometer. The results show that first-surface mirrors top-protected with amorphous Aluminum Oxide (1μm thick) layer show a higher specular reflectance compared to second-surface mirrors, which makes Al 2 O 3 -top-protected front-surface mirrors the best candidate in CSP application. The deposition of the Al 2 O 3 layer was conducted using the Ion Layer Gas Reaction (Spray-ILGAR) technique, which did not alter the optical properties of the unprotected mirrors, conserving a high specular reflectance of the Silver-based first-surface mirrors (94% in the Near Infrared range).

Heat Control simulation for variothermal injection moulding moulds using infrared radiation

“…In front of the actual substrate material there are natural oxide layers and chemical impurities that influence the absorption [44]. Figure 8 shows the comparison of the degrees of reflection between pure aluminium [45] and aluminium oxide Al 2 O 3 [46].…”

Photo-Induced Self-Assembly of Silver Nanoparticles for Rapid Generation of First and Second Surface Mirrors

“…These mirrors are commonly referred to as front or second surface mirrors depending on the position of the reflective metal layer on the front or rear side of the glass substrate. 1 In fact, glass is an ideal material to be coated with a reflective metal top layer to create a mirror. It offers an optimal combination of thermal, mechanical, and optical properties that provide protection against degradation factors and aggressive external conditions.…”

“…Nowadays, mirrors of all types are part of most people’s daily lives, from smart coated windows and bathroom equipment, car rear-view mirrors, and optical instruments (microscopes and telescopes) to laser reading systems such as compact disc players and barcode scanners, and so on. These mirrors are commonly referred to as front or second surface mirrors depending on the position of the reflective metal layer on the front or rear side of the glass substrate . In fact, glass is an ideal material to be coated with a reflective metal top layer to create a mirror.…”

Metallic Adhesive Layers for Ag‐Based First Surface Mirrors

“…Commercial mirrors are usually second surface mirrors, which means that the reflective coating is placed on the underside of a transparent substrate. [1] The drawback of these is that the total solar reflectivity is reduced through absorption losses and internal reflections of the substrate. [2] A first surface mirror on the other hand, has the reflective layer deposited on the front of the substrate, thus, the light is directly reflected by the top surface.…”